public class ReadFormFile
{
// 以二进制方式读取文件 常用于读取二进制文件 图片 声音 视频等
public static void readByBytes(String fileName)
{
File file = new File(fileName);
InputStream in = null;
try
{
System.out.println("一次读取一个字节");
in = new FileInputStream(file);
int temp;// temp存放的是编码表对应的字符编码
while ((temp = in.read()) != -1)
{
System.out.println(temp);
// System.out.write(temp);
}
// 文件末尾输出-1
in.close();
} catch (IOException e)
{
e.printStackTrace();
return;
}
}
public static void readByteMore(String fileName)
{
InputStream in = null;
File file = new File(fileName);
try
{
System.out.println("一次读取多个字节");
byte[] temp = new byte[1024];
int buffer = 0;
in = new FileInputStream(fileName);
while ((buffer = in.read(temp)) != -1)
{
// System.out.println(buffer );
System.out.write(temp, 0, buffer);
}
System.out.println(buffer);
in.close();
} catch (Exception e)
{
e.printStackTrace();
}
}
//以字符方式读取文件
public static void readByChar(String fileName)
{
File file = new File(fileName);
InputStreamReader reader = null;
try
{
reader = new InputStreamReader(new FileInputStream(file));
int temp = 0;
while ((temp = reader.read()) != -1)
{
System.out.print((char) temp);
}
reader.close();
} catch (Exception e)
{
// TODO: handle exception
e.printStackTrace();
}
}
public static void readByCharMore(String fileName)
{
File file = new File(fileName);
InputStreamReader reader = null;
try
{
reader = new InputStreamReader(new FileInputStream(file));
int charLength = 0;
char[] temp = new char[30];
while ((charLength = reader.read(temp)) != -1)
{
System.out.println(temp);
}
} catch (Exception e)
{
// TODO: handle exception
e.printStackTrace();
}
}
public static void writeFileByByte(String fileName)// 以字节为单位写文件
{
File file = new File(fileName);
OutputStream out = null;
try
{
String wenjian = "haha";
out = new FileOutputStream(file);
Scanner scanner = new Scanner(System.in);
byte[] bytes = null;
while (!wenjian.equals("@"))
{
wenjian = scanner.next();
bytes = wenjian.getBytes();// 将字符串转换成字节数组
out.write(bytes);
}
out.close();
} catch (Exception e)
{
e.printStackTrace();
}
}
public static void writeByChar(String fileName)//以字符为单位写入字符串
{
File file = new File(fileName);
OutputStreamWriter outputStreamWriter = null;
try
{
outputStreamWriter = new OutputStreamWriter(new FileOutputStream(file));
String string = "cui meng meng sha gua";
outputStreamWriter.write(string);
outputStreamWriter.close();
} catch (Exception e)
{
e.printStackTrace();
}
}
public static void writeByLine(String fileName)//格式化写入文件 每次写入一行
{
File file=new File(fileName);
PrintWriter writer=null;
try
{
writer=new PrintWriter(new FileOutputStream(file));//通常用于格式化读入
writer.println(123);//此时的123是int型的
writer.println("cui meng meng sha gua");//字符串
writer.flush();//将流中的字节刷新到文件中
writer.close();
} catch (Exception e)
{
// TODO: handle exception
e.printStackTrace();
}
}
public static void main(String[] args)
{
String fileName = "C:/Users/Administrator/Desktop/yyy.txt";
// ReadFormFile.readByBytes(fileName);
// ReadFormFile.readByteMore(fileName);
// ReadFormFile.readByChar(fileName);
// ReadFormFile.readByCharMore(fileName);
// ReadFormFile.writeFileByByte(fileName);
//ReadFormFile.writeByChar(fileName);
ReadFormFile.writeByLine(fileName);
}
}